1. Field of the Invention
The invention relates to an air chuck, more particularly to an air chuck that can better withstand wear and that can buffer and compensate instantaneous expansion of an air bladder.
2. Description of the Related Art
An air chuck is rotatably mounted on a mandrel of a machine, and is expandable by use of pressurized air so as to hold a roll of web material, such as paper, rubber, plastic, metal, fabric, wire, or the like, thereon.
Referring to FIG. 1, a conventional air chuck 1 includes two end caps 11, 12, and a generally cylindrical air bladder 13 mounted between the end caps 11, 12 and formed from a rubber material. The air bladder 13 confines an air chamber 131 and has an axial through hole 132 communicated with cap holes 111, 121 in the end caps 11, 12. The end cap 11 is further provided with an air passage 112 communicated with the air chamber 131, and an inflating valve 14 is connected to the air passage 112 for inflating or deflating the air chamber 131. When the inflating valve 14 is connected to a pressurized air source, pressurized air is supplied to the air chamber 131 to inflate the air chamber 131 so as to expand the air bladder 13 in radial outward directions, thereby holding tightly a roll 15 of web material on the air chuck 1 and a mandrel 16 extending through the axial through hole 132. As such, rotation of the mandrel 16 will bring the air chuck 1 and the roll 15 to rotate therewith so as to feed or wind the web material on the roll 15.
However, as a considerably high pressure is required to inflate the air bladder 13 to thereby retain the roll 15 on the air chuck 1, instantaneous expansion of the air bladder 13 may result in breaking or explosion of the air bladder 13, which is dangerous. Moreover, replacement of the air bladder 13 is inconvenient and costly.
Therefore, the main object of the present invention is to provide an air chuck that can better withstand wear and that can buffer and compensate instantaneous expansion of an air bladder. Accordingly, an air chuck of the present invention includes a tubular core member, a resilient deformable air bladder, an air passage, a pair of end caps, a plurality of angularly spaced apart connecting rods, a plurality of angularly spaced apart biasing members, and a plurality of hollow leaf members. The core member has opposite first and second core end portions and a core axis. The air bladder is sleeved on the core member, and has opposite first and second bladder end segments retained respectively on the core member, and an intermediate bladder segment disposed between the first and second bladder end segments. The bladder forms an inflatable air chamber that extends around the core member. The air passage is in fluid communication with the air chamber for inflating and deflating the air chamber. The end caps are mounted respectively on the first and second core end portions. The connecting rods are disposed circumferentially around the air bladder. Each of the connecting rods has a rod axis parallel to the core axis, and opposite rod ends mounted respectively on the end caps. The biasing members are disposed circumferentially around the air bladder. Each of the biasing members has a coil spring section with a spring axis parallel to the core axis, and a pair of coupling end sections that extend in opposite directions from the coil spring section and that are mounted respectively on the end caps. Each of the biasing members is disposed between an adjacent pair of the connecting rods. The leaf members are disposed circumferentially around the air bladder. Each of the leaf members includes a curved inner wall segment, a curved outer wall segment disposed radially, spacedly and outwardly from the inner wall segment, and a pair of lateral wall segments that interconnect the inner and outer wall segments. Each of the leaf members confines a set of the connecting rods and a set of the biasing members therein. Inflation of the air chamber enables the air bladder to urge the leaf members in radial outward directions relative to the core axis such that the inner wall segments abut against the coil spring sections of the biasing members and such that radial outward movements of the leaf members are limited by the connecting rods.